In LED applications, TRIAC dimmers are popularly used. Conventionally, the LED system works at boundary conduction mode (BCM). Two approaches are used to shape the input current of the LED driver for the optimization for the TRIAC dimmer's latching current requirement under BCM mode. The first one is to add a big RC circuit to supply the latching current for the dimmer. However, this method increases the power loss. The second one is to shape the input current by increasing the peak current of power device to supply for sufficient latching current. However, this method brings higher stress of the power components, and increases the circuit size and the cost.